Limited roof space - splitting arrays

[Hotlush]

Roof on the house is broadly south facing but has a dormer which limits the number of panels to 4, maybe 5, with a small amount of shading for a few hours a day.
Two to each side of the dormer, vertically, and one in front, horizontal.

We had already been considering a garden building at the bottom of our garden, 18'w by 10'd, again south facing.
Spoken to a local company and they're reasonably confident they could build one that could hold an array.

Building would be roughly 23 metres from the electricity meter in a mostly straight run and, ideally, we'd want the inverter/batteries/etc. in it.
(Very) rough sizing says we could fit potentially 5-8 panels on the building.
Five at the front, vertical alignment, with three behind in a horizontal alignment.
Would need some kind of risers as the building pent will be so small it might as well be considered a flat roof.
Depending on how they're laid out I suspect there may be a small amount of shading of the back panels in that configuration.

So questions are;
[list]
[li]Given the potential shading I'm guessing we would be best looking at DC optimizers or microinverters?[/li]
[li]We would need to run cable from the house array, either directly to the inverter or to the building array, and then a second cable run from the inverter back to the meter?
So (23m x 2) + ~9m (2.5 story and assuming it just goes down side of house) = 55m, 23m AC, 32 DC[/li]
[/list]

So does that all look practicable and any obvious pitfalls or stoppers?
Have I got any assumptions obviously wrong?

Thanks.

[Peter on the south coast]

Ok  So I am a solar saddo
There is no substitute for fitting as many panels as possible. I see no big problem in having 2 separate strings. one for the house and one from the garden.
Originally the FIT scheme required solar panels to be roof mounted
In the US there are many systems which are ground mounted. You can also install a mirror at the base of the panels, so in less than optimum conditions this will boost out put. Here the newer solar farms tend to have them high enough to have sheep grazing in the same field.
1KW of output tends to require something that will take 50kg and be about 5 square metres.
Personally I installed a 4kw system 11 years ago. Last September I went OTT and installed another 5.6kw on our south roof and 4.8kw on the East where we have a dormer. This gives me a ridiculous amount of electricity. We also have 4 x 6.5kw of batteries. This enables us to run an EV, and the whole of the house including hot water for about 10 months. We know we will get about 14,000kw/year. Last month our output was 1320kw.
Our latest panels are Hyundai shingle of 400watts each. They have 10 sections (shingles) so if shade occurs only the shaded part gets knocked out. Like you we have a dormer on the east elevation.
If you are having a shed built for the panels make sure it is south facing and has a roof with an optimal angle. Personally I would try and build a pupose made support. By the time you have re-inforced the shed, made sure the rails will not allow water in, the expense will not be slight.  The Hyundai's are 1719mm x 1140mm. My view is that there is nothing to stop you from doing what you want in your own garden. Panels are no longer subsidised. I am lucky to have a lot of roof space, but otherwise I might have used the garden..........wife permitting
Finally I recommend you look at hybrid inverters. You will then be able to add batteries at the same time or later

Attached is a picture of our new system mid installation. There is a big Hybrid inverter on the left and a standard one on the right.

Sorry attachment did not work 

Peter